Molding processes are frequently employed in the manufacture of optical elements (for example, see Patent Document 1). For example, in the case of a molding process for a phase Fresnel lens, which is a bonded-multilayer diffractive optical element, a first resin material is packed into a gap between a disk-shaped glass substrate and a molding die positioned in proximity to the glass substrate, and a first resin layer having a diffraction grating is molded. Then, a molding die is pressed against a second resin material having a different refractive index than the first resin material, which has been dripped onto the first resin layer, and a second resin layer is molded. Consequently, a bonded-multilayer diffractive optical element be molded.